An ongoing concern in the area of digital rights management is the unauthorized copying of content that is released into the marketplace. Numerous schemes and techniques have been introduced to discourage and/or prevent such unauthorized copying, with varying degrees of success.
Taking Digital Video Discs (DVDs) as an example of such content, DVDs can be protected from illegal or unauthorized copying by at least two techniques: Macrovision and CSS. Both of these techniques attempt to make it difficult or impossible to make a usable copy of a DVD. However, both of these techniques can be bypassed with readily available and inexpensive tools. Additionally, neither technique is supported on DVD-R media.
The use of watermarks to discourage copying is a stronger approach, but current systems do not enable watermarking in the context of retail sales. This is due to at least two reasons. First, retail sales typically involve media that have been previously replicated in mass. Therefore, these mass-produced media cannot contain watermarks that are individualized for particular purchasers, because the identity of the purchaser is not known when the DVD is replicated. Second, limitations of current watermark techniques may not fully lend themselves to the retail context.